The proposed work will attempt to uncover the nature of the T lymphocyte surface receptors and also to elucidate their source as well as the role they play in the recognition and reaction to foreign histocompatibility and tumor antigens. We will also look at the apparent increase in antibody forming cells during an in-vitro allograft rejection reaction (ARR) to determine what role if any they play in lymphocyte mediated cytotoxicity. In addition we intend to extend our work in immunopathology and inflammation which showed that human leukocyte granule enzymes are not cytotoxic in-vitro, by using different cell lines, as well as several different lines of investigation which now appear quite promising. Still another group of studies will be concerned with the role of cell mediated immunity in the progress of tissue destructive phase of inflammatory periodontal disease. In the near future also, pilot studies will begin which will in essence make comparisons between two groups of patients with gingival inflammation caused by accumulations of bacterial plaque. If one group the inflammation has resulted in destruction of periodontal structures as evidenced by existence of periodontal pockets whereas in the other group of patients although plaque and inflammation are present, there are no pockets. The results of such comparisons when the parameters are expanded sufficiently, may very well result in elucidating the vary nature of periodontal disease.